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Peter Michael Abbamonte

Associate Professor

Ph.D. Physics, University of Illinois-Urbana, 1999

Peter Michael Abbamonte
Office
104 Seitz Materials Research Lab
Phone
217.244.4861
Fax
217.244.8544
Email
abbamontatillinois.edu

Professor Abbamonte received his Ph.D in physics from the University of Illinois at Urbana-Champaign in 1999. After receiving his Ph.D, he went to the University of Groningen in The Netherlands on an IRFAP fellowship from the National Science Foundation. In 2001, he returned to the U.S. as a postdoc in biophysics at Cornell University, and joined the scientific staff at Brookhaven National Laboratory in 2003. He joined the Department of Physics in August of 2005. 

Professor Abbamonte is regarded as one of the originators of the new technique of resonant soft x-ray scattering, which he has used, among other things, to show that stripes in copper-oxide superconductors are charged. This technique is now in use or under commissioning at every major synchrotron facility in the world. He is also known for his solution to the phase problem for inelastic x-ray scattering, which has provided a means to perform real-time imaging of electron motion in condensed matter, with attosecond time resolution.

Research Interests:

  • electron self-organization in condensed matter, stripe phases, topological order; edge and interface effects in oxide devices; quantum phase transitions; collective excitations in interacting electron systems.

Other Activities

Our group is devoted to the study of elementary quantum phenomena in condensed matter, such as collective excitations in interacting electron systems, electron-self organization in doped Mott insulators (viz. “stripes”) and other forms of topological order, and edge states and interface effects in oxide devices (see Research). Our work involves a combination of in-house sample fabrication and characterization, and x-ray scattering experiments national facilities. Most of our scattering experiments are done at beam line X1B at the National Synchrotron Light Source at Brookhaven National Laboratory (Upton, NY), and Sector 9-ID at the Advanced Photon Source at Argonne National Laboratory (Argonne, IL).

Stripe order in doped Mott insulators
Charge correlations indicating the presence of strip order in a doped Mott insulator, measured with resonant x-ray scatteringThe Mott insulator is the fundamental parent phase of most materials we refer to as "correlated electron systems." If carriers are doped into a Mott insulator (e.g., by removing a spin), there is a competition between their tendency to delocalize — to minimize kinetic energy — and the desire of the system to retain valence bond order.

One of our projects is to study the degree to which this competition tends to drive phase segregation, perhaps into charged magnetic domain lines, colloquially referred to as "stripes." This project is a close collaboration with E. Fradkin.

The figure shows charge correlations indicating the presence of strip order in a doped Mott insulator, measured with resonant x-ray scattering.

Edge and interface states in transition metal oxide devices
Superlattice reflections (above) from a heterostructure of LaMnO_3 and SrMnO_3 (below). The presence of a reflection at L = 3 indicates that the interfaces are electronically reconstructed.The transition metal oxides, most of which are correlated electron systems (usually doped Mott insulators) exhibit many exotic phases.

Even more intricate behavior may be realized, however, near an edge or at the interface between two such systems, where translational symmetry is explicitly broken. This might provide a route to new devices.

The purpose of this project is to explore what new phases exist in heterostructures and patterned arrays of such systems. This project is a close collaboration with the Eckstein group, which grows the structures we use for e-beam patterning and for scattering experiments.

This figure shows superlattice reflections from a heterostructure of LaMnO3 (top) and SrMnO3 (bottom). The presence of a reflection at L = 3 indicates that the interfaces are electronically reconstructed.

Quantum phase transitions

a diamond anvil cell used for x-ray scattering experiments to study the behavior of soft modes through a quantum phase transitionIt is possible for a system to undergo a change of state, even at zero temperature, as a function of some external parameter such as pressure or applied magnetic field. Such a change cannot be described in terms of a classical balance between energy and entropy because entropy is irrelevant at T = 0.

The purpose of this project is to study how such phase transitions occur, particularly in materials that involve broken translational symmetry such as a charge density wave. We are particularly interested in the behavior of soft modes, and whether in specific cases their dynamics can be tied to the concept of entanglement entropy. This project is done in close collaboration with the Cooper group.

The photograph shows a diamond anvil cell used for x-ray scattering experiments to study the behavior of soft modes through a quantum phase transition.

Collective excitations in interacting systems

A noninteracting system exhibits only single-particle excitations (i.e., electron-hole pairs). If interactions are present, collective excitations may arise that do not necessarily obey Fermi statistics. The simplest example is the “plasmon,” a spin 0 boson excitation of the interacting electron gas, which is responsible for screening in most real materials.

The purpose of this project is to use inelastic x-ray scattering to study collective electronic excitations in various (weakly or strongly) interacting systems. We are particularly interested in applying phase retrieval algorithms to image such excitations in real space and time. This project is a collaboration with the Cahill and Zuo groups in MatSE.

Shown below is an image of the plasmon excitation in pyrolitic graphite, measured with inelastic x-ray scattering. This excitation, which screens charge in this system, is necessary for the existence of Dirac points in graphene.

Image of the plasmon excitation in pyrolitic graphite, measured with inelastic x-ray scattering. This excitation, which screens charge in this system, is necessary for the existence of Dirac points in graphene

For more information:

NSLS Beam Line X1B
Abbamonte Research Group

Honors and awards:

  • Arnold O. Beckman Fellow, Center for Advanced Study (2008-2009).
  • NSF Intl. Research Fellowship, 2000-2001

Selected Publications: